I. Field of the Invention
The present invention relates generally to wireless telephone systems, and more particularly to multi-band wireless telephones in vehicles.
II. Description of the Related Art
Wireless telephones are in widespread use because of the convenience they afford in personal communications. Wireless telephone technology continues to advance, producing better wireless communication systems while older systems nevertheless remain in use.
For example, earlier wireless telephone systems use analog communication principles and a communication frequency band of around 800 MHz, whereas more recent systems have been introduced that use digital communication principles in a frequency band around 1900 MHz. In some geographic regions, both of these systems are in use, and in some circumstances the older systems that operate around 800 MHz have been or will be converted to use digital communication principles.
In any event, because of the different frequencies used by different wireless telephone systems, the frequency at which a user's wireless telephone must operate might change from region to region. Indeed, some users in a given region might require telephones that operate at a first frequency while other users in the same region must communicate using a second frequency. In some instances, more than two frequencies might be in operation in a single area.
Recognizing the above-mentioned problem, the present invention recognizes that it is desirable to provide wireless telephones that can communicate using one of at least two (and perhaps more) frequencies, so that the telephones can be used in conjunction with more than one system. In other words, the present invention recognizes that it is desirable that one wireless telephone model be useful in more than one communication system, to increase the operational flexibility of the telephone. As a less desirable alternative, two telephones, each operating at a single respective frequency, can be provided.
It happens that to improve communication when a wireless telephone is used inside the passenger compartment of a vehicle, it is advantageous to provide a coupling device on the vehicle that, along with an associated antenna referred to as a radiator, in essence establishes a low-noise transmission path from the telephone to the air interface outside the vehicle. Among other considerations, the above factors, as inventively recognized herein, imply that a wireless telephone, when used in a vehicle, should be associated with signal transmission coupling devices that effectively transmit signals in both of two frequency bands to and from the telephone in the interior of the vehicle.
From the above discussion, however, it may be appreciated that existing wireless telephone coupling devices used in vehicles are designed for single frequency use only. Consequently, such existing devices, when used with a multiple frequency telephone or telephones, would effectively couple, to the air interface, signals in one of the telephone's frequency bands, but, unfortunately, not more. A need is thus recognized to provide a coupling device with associated multiple band antenna in a vehicle that effectively couples signals in two or more frequency bands to the air interface of a wireless telephone communication system.
Accordingly, it is a purpose of the present invention to provide a coupling device that can be associated with a vehicle for establishing a low-noise communication pathway to and from a wireless telephone inside the vehicle. Another purpose of the present invention is to provide a coupler in a vehicle that can effectively couple signals in at least two frequency bands across a window of the vehicle. Yet another purpose of the present invention is to provide a multiple (dual) band radiator in a vehicle that can effectively conduct signals in each of two frequency bands. Still another purpose of the present invention is to provide a coupling device for coupling multiple band signals to and from a wireless telephone in a vehicle, such that the coupling device is easy to use and cost-effective to manufacture and implement.